[Negriz]

Empezado por cHackAll

__fastcall TForm2::TForm2(TComponent* Owner)
  : TForm(Owner)
{
 SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) | WS_EX_LAYERED);
 SetLayeredWindowAttributes(Handle, 0, 255, LWA_ALPHA);
}

void __fastcall TForm2::FormActivate(TObject *Sender)
{
 for (int blend = 200; blend < 256; blend+=5)
  {
   SetLayeredWindowAttributes(Handle, 0, blend, LWA_ALPHA);
   Sleep(10);
  }
}

void __fastcall TForm2::FormDeactivate(TObject *Sender)
{
 for (int blend = 255; blend > 200; blend-=5)
  {
   SetLayeredWindowAttributes(Handle, 0, blend, LWA_ALPHA);
   Sleep(10);
  }
}

gracias lo voy a probar.